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  <div class="section" id="boost-hof-lift">
<h1>BOOST_HOF_LIFT<a class="headerlink" href="#boost-hof-lift" title="Permalink to this heading">¶</a></h1>
<div class="section" id="header">
<h2>Header<a class="headerlink" href="#header" title="Permalink to this heading">¶</a></h2>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;boost/hof/lift.hpp&gt;</span><span class="cp"></span>
</pre></div>
</div>
</div>
<div class="section" id="description">
<h2>Description<a class="headerlink" href="#description" title="Permalink to this heading">¶</a></h2>
<p>The macros <code class="docutils literal notranslate"><span class="pre">BOOST_HOF_LIFT</span></code> and <code class="docutils literal notranslate"><span class="pre">BOOST_HOF_LIFT_CLASS</span></code> provide a lift operator that
will wrap a template function in a function object so it can be passed to
higher-order functions. The <code class="docutils literal notranslate"><span class="pre">BOOST_HOF_LIFT</span></code> macro will wrap the function using
a generic lambda. As such, it will not preserve <code class="docutils literal notranslate"><span class="pre">constexpr</span></code>. The
<code class="docutils literal notranslate"><span class="pre">BOOST_HOF_LIFT_CLASS</span></code> can be used to declare a class that will wrap function.
This will preserve <code class="docutils literal notranslate"><span class="pre">constexpr</span></code> and it can be used on older compilers that
don’t support generic lambdas yet.</p>
</div>
<div class="section" id="limitation">
<h2>Limitation<a class="headerlink" href="#limitation" title="Permalink to this heading">¶</a></h2>
<p>In C++14, <code class="docutils literal notranslate"><span class="pre">BOOST_HOF_LIFT</span></code> doesn’t support <code class="docutils literal notranslate"><span class="pre">constexpr</span></code> due to using a generic
lambda. Instead, <code class="docutils literal notranslate"><span class="pre">BOOST_HOF_LIFT_CLASS</span></code> can be used. In C++17, there is no such
limitation.</p>
</div>
<div class="section" id="synopsis">
<h2>Synopsis<a class="headerlink" href="#synopsis" title="Permalink to this heading">¶</a></h2>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="c1">// Wrap the function in a generic lambda</span>
<span class="cp">#define BOOST_HOF_LIFT(...)</span>

<span class="c1">// Declare a class named `name` that will forward to the function</span>
<span class="cp">#define BOOST_HOF_LIFT_CLASS(name, ...)</span>
</pre></div>
</div>
</div>
<div class="section" id="example">
<h2>Example<a class="headerlink" href="#example" title="Permalink to this heading">¶</a></h2>
<div class="highlight-cpp notranslate"><div class="highlight"><pre><span></span><span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;boost/hof.hpp&gt;</span><span class="cp"></span>
<span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;cassert&gt;</span><span class="cp"></span>
<span class="cp">#include</span><span class="w"> </span><span class="cpf">&lt;algorithm&gt;</span><span class="cp"></span>

<span class="c1">// Declare the class `max_f`</span>
<span class="n">BOOST_HOF_LIFT_CLASS</span><span class="p">(</span><span class="n">max_f</span><span class="p">,</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">max</span><span class="p">);</span><span class="w"></span>

<span class="kt">int</span><span class="w"> </span><span class="nf">main</span><span class="p">()</span><span class="w"> </span><span class="p">{</span><span class="w"></span>
<span class="w">    </span><span class="k">auto</span><span class="w"> </span><span class="n">my_max</span><span class="w"> </span><span class="o">=</span><span class="w"> </span><span class="n">BOOST_HOF_LIFT</span><span class="p">(</span><span class="n">std</span><span class="o">::</span><span class="n">max</span><span class="p">);</span><span class="w"></span>
<span class="w">    </span><span class="n">assert</span><span class="p">(</span><span class="n">my_max</span><span class="p">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p">)</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">max</span><span class="p">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p">));</span><span class="w"></span>
<span class="w">    </span><span class="n">assert</span><span class="p">(</span><span class="n">max_f</span><span class="p">()(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p">)</span><span class="w"> </span><span class="o">==</span><span class="w"> </span><span class="n">std</span><span class="o">::</span><span class="n">max</span><span class="p">(</span><span class="mi">3</span><span class="p">,</span><span class="w"> </span><span class="mi">4</span><span class="p">));</span><span class="w"></span>
<span class="p">}</span><span class="w"></span>
</pre></div>
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